The last part really points out the mess that the current browsers are in:

and Chrome called itself Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.27 Safari/525.13, and the user agent string was a complete mess, and near useless, and everyone pretended to be everyone else, and confusion abounded

How is any website meant to know what rules to use now?

UPDATE: Here is a great resource for testing out different user-agents: